A known opening-and-closing member may be provided with an apparatus which is for detecting pinch or entrapment of, for example, an object during an automatic closing operation of the opening-and-closing member. For example, JP3931732B (hereinafter referred to as Patent reference 1) discloses a known pinch detection apparatus provided at a sunroof of a vehicle. According to the known pinch detection apparatus disclosed in Patent reference 1, first, reference load data is calculated from a fluctuating rotation speed of a motor during a closing operation in a case where a predetermined condition is established, and is stored. At the closing operation after the storage of the reference load data, a difference between drive data calculated from the fluctuating rotation speed and the reference load data is calculated. On the basis of comparison between the difference and a threshold, that is, on the basis of a comparison result, pinch detection is performed. Conversion from data of the fluctuating rotation speed to data of load fluctuation is performed on the basis of a known function that is related to a rotation speed of a motor and a generated torque.
In addition, JP2010-110171A (hereinafter referred to as Patent reference 2) discloses a known motor control apparatus performing a pinch detection at, for example, a window of a vehicle. According to the known motor control apparatus disclosed in Patent reference 2, a relationship among a motor temperature and motor characteristics, and an estimated load is mapped. At a closing operation of an opening-and-closing member, presence or absence of the pinch is determined on the basis of the estimated load derived from the motor temperature and the motor characteristics according to the map. More specifically, the map, which indicates the motor characteristics for a classification of motor temperature ranges (−30° C.˜0° C., 0° C.˜40° C., 40° C.˜80° C.), plural driving voltages (8V, 12V, 16V) and motor rotation speeds, is preset. From the motor temperature, the driving voltage and the motor rotation speed which are detected, a processing for estimating the load is performed, referring to the map. Here, the motor temperature is detected by a temperature sensor provided in a vicinity of the motor and the above-explained load estimation is performed on the basis of the detected temperature.
According to the apparatus of the Patent reference 1, however, it is not considered that a relationship between the rotation speed and the load of the motor fluctuates depending on an environmental temperature. As will be stated below in detail, the relationship between the rotation speed of the motor and the load of the motor substantially shows to a negative linear function, however, an inclination of the function changes depending on the environmental temperature. Thus, in a case where the environmental temperature at the time of calculating the reference load data and the environmental temperature at the time of calculating the drive data differ from each other, the actual difference between the reference load data and the drive data, and the calculated difference between the reference load data and the drive data do not coincide with each other. Consequently, according to the apparatus of the Patent reference 1, the relationship between the difference between the reference load data and the drive data, and the detection threshold changes depending on the temperature, and therefore it is difficult for pinch detection with high accuracy to be performed.
As a first problem of the apparatus of the Patent reference 2, the temperature sensor that accurately detects the temperature of the motor is needed because the map, which indicates the relationship between an absolute temperature (temperature range) of the motor and the motor characteristics, is used. Thus, the temperature sensor with high accuracy needs to be provided in a vicinity of the motor, which increases an introduction cost. Secondly, the load estimation performed by using the initial characteristic map does not necessarily remain useful or usable thereafter because the relationship between the motor temperature and the motor characteristics changes due to, for example, an aging deterioration of the motor. Therefore, the initial detection accuracy may not be maintained after the apparatus is used for many years.
A need thus exists for a pinch detection apparatus for an opening-and-closing member and an opening-and-closing member apparatus, which are not susceptible to the drawback mentioned above.